Towards a Uniform Theory of Effectful State Machines

Using recent developments in coalgebraic and monad-based semantics, we present a uniform study of various notions of machines, e.g. finite state machines, multi-stack machines, Turing machines, valence automata, and weighted automata. They are instances of Jacobs' notion of a T-automaton, where T is a monad. We show that the generic language semantics for T-automata correctly instantiates the usual language semantics for a number of known classes of machines/languages, including regular, context-free, recursively-enumerable and various subclasses of context free languages (e.g. deterministic and real-time ones). Moreover, our approach provides new generic techniques for studying the expressivity power of various machine-based models.Comment: final version accepted by TOC

The Power of Convex Algebras

Probabilistic automata (PA) combine probability and nondeterminism. They can be given different semantics, like strong bisimilarity, convex bisimilarity, or (more recently) distribution bisimilarity. The latter is based on the view of PA as transformers of probability distributions, also called belief states, and promotes distributions to first-class citizens. We give a coalgebraic account of the latter semantics, and explain the genesis of the belief-state transformer from a PA. To do so, we make explicit the convex algebraic structure present in PA and identify belief-state transformers as transition systems with state space that carries a convex algebra. As a consequence of our abstract approach, we can give a sound proof technique which we call bisimulation up-to convex hull.Comment: Full (extended) version of a CONCUR 2017 paper, to be submitted to LMC

Social fund support of microfinance : a review of implementation experience

The case studies were developed in order to help Bank task team leaders, and their client country counterparts, design and support effective microfinance components, within social funds. The case studies aim to highlight best practice, as well as challenges for designing, and implementing a microfinance component within a multi-sectoral project. Based on lessons learned from these case studies, a set of guidelines were developed, available from the Social Protection Advisory Service, or the Social Funds website.Banks&Banking Reform,Rural Finance,Private Participation in Infrastructure,Agricultural Research,Microfinance

A Regional Human Development Index for Portugal

In a report from 2008 the Organization for Economic Cooperation and Development came to the conclusion that Portugal is still a country very much marked by regional asymmetries and in need of better regional governance mechanisms and policies. In the face of these conclusions it becomes important to address the issue of constructing an index of regional development for Portuguese regions to better assess the evolution of the differential between regions. We propose a regional human development index for Portugal at the NUTS III level, based on the methodology of the Human Development Index (HDI) from the United Nations Development Programme (UNDP). Results show us a country that has most of the highest ranked NUTS III positioned in the coastline, although some interior NUTS III regions improve their relative positions in the ranking between 2004 and 2008. Additionally to the traditional dimensions of the HDI, we also added two dimensions, that we choose to include, given the main criticisms pointed in the literature to the HDI - governance and environment. Results show some significative differences when we add the environment dimension, but in terms of governance they don't change significantly.Human Development Index, Regional Asymmetries, Portugal.

Conditional Transition Systems with Upgrades

We introduce a variant of transition systems, where activation of transitions depends on conditions of the environment and upgrades during runtime potentially create additional transitions. Using a cornerstone result in lattice theory, we show that such transition systems can be modelled in two ways: as conditional transition systems (CTS) with a partial order on conditions, or as lattice transition systems (LaTS), where transitions are labelled with the elements from a distributive lattice. We define equivalent notions of bisimilarity for both variants and characterise them via a bisimulation game. We explain how conditional transition systems are related to featured transition systems for the modelling of software product lines. Furthermore, we show how to compute bisimilarity symbolically via BDDs by defining an operation on BDDs that approximates an element of a Boolean algebra into a lattice. We have implemented our procedure and provide runtime results

Can Core Flows inferred from Geomagnetic Field Models explain the Earth's Dynamo?

We test the ability of large scale velocity fields inferred from geomagnetic secular variation data to produce the global magnetic field of the Earth.Our kinematic dynamo calculations use quasi-geostrophic (QG) flows inverted from geomagnetic field models which, as such, incorporate flow structures that are Earth-like and may be important for the geodynamo.Furthermore, the QG hypothesis allows straightforward prolongation of the flow from the core surface to the bulk.As expected from previous studies, we check that a simple quasi-geostrophic flow is not able to sustain the magnetic field against ohmic decay.Additional complexity is then introduced in the flow, inspired by the action of the Lorentz force.Indeed, on centenial time-scales, the Lorentz force can balance the Coriolis force and strict quasi-geostrophy may not be the best ansatz.When the columnar flow is modified to account for the action of the Lorentz force, magnetic field is generated for Elsasser numbers larger than 0.25 and magnetic Reynolds numbers larger than 100.This suggests that our large scale flow captures the relevant features for the generation of the Earth's magnetic field and that the invisible small scale flow may not be directly involved in this process.Near the threshold, the resulting magnetic field is dominated by an axial dipole, with some reversed flux patches.Time-dependence is also considered, derived from principal component analysis applied to the inverted flows.We find that time periods from 120 to 50 years do not affect the mean growth rate of the kinematic dynamos.Finally we notice the footprint of the inner-core in the magnetic field generated deep in the bulk of the shell, although we did not include one in our computations

Teatro Universitário em Coimbra na década de 1980

After the democratic revolution, alongside with all political changes, the biennium of 1975‑76 was a transition period also rich in diverse cultural experiences and representations. Usually within academic sites, which then integrated a heterogeneous urban young middle class, emerged experiences in the field of theatre, indicating an attitude of independence. This article intends to recognize the strategies developed by a significant sector of students in order to build processes of construction and definition of urban cultural resistance throughout this period

Azores tourism product perceptions : the Influence of the country of origin

This study focused on the Autonomous Region of the Azores (ARA), which has some features that are considered favorable to the development of tourism and to the interest in the tourism product. However, the region’s geographical dispersion, its high dependence on transportation and the seasonality of the industry constrain its development. The present research aimed to assess tourists’ perception of certain costs (living, accommodation, plane ticket, and transportation to/from the airport), and whether these differ between tourists of different nationalities. The findings show that tourists, both residents and non-residents, have the perception that the cost of living and of the plane ticket are high, while the cost of accommodation and of transportation to the airport is considered normal by most respondents. We concluded that the models differ when applied to residents and non-residents. For non-residents, living in certain countries induces them to express differences in the perception of the costs studied, when compared to individuals that live in other countries.N/

Guarded Kleene Algebra with Tests: Verification of Uninterpreted Programs in Nearly Linear Time (Invited Talk)

Guarded Kleene Algebra with Tests (GKAT) is a variation on Kleene Algebra with Tests (KAT) that arises by restricting the union (+) and iteration (*) operations from KAT to predicate-guarded versions. We develop the (co)algebraic theory of GKAT and show how it can be efficiently used to reason about imperative programs. In contrast to KAT, whose equational theory is PSPACE-complete, we show that the equational theory of GKAT is (almost) linear time. We also provide a full Kleene theorem and prove completeness for an analogue of Salomaa\u27s axiomatization of Kleene Algebra. We will also discuss how this result has practical implications in the verification of programs, with examples from network and probabilistic programming. This is joint work with Nate Foster, Justin Hsu, Tobias Kappe, Dexter Kozen, and Steffen Smolka